This invention generally relates to apparatus for removing and transporting articles from molds. More specifically, the present invention relates to such apparatus that is very well suited for carrying the articles, in a very short period of time, away from the molds and depositing the articles for further processing in a high speed, automated production system.
Recently, attention has been directed toward forming contact lenses in an automated molding system. In such a system, each lens is formed by sandwiching a monomer between front and back mold sections. The monomer is polymerized to form a lens, which is then removed from the mold sections, further treated and then packaged for consumer use.
The mold sections used in the above-outlined process may themselves be formed in injection molding or compression molding processes. These mold sections may be made from the family of thermoplastics, for example polystyrene, which is an excellent material for making these mold sections. Polystyrene does not chemically react with the hydrophilic material used to make the contact lens, therefore, very high quality contact lenses may be formed in polystyrene molds. In addition, polystyrene is widely available and relatively inexpensive. Because of the ease and low cost with which polystyrene mold sections may be made and then used to mold contact lenses, each pair of polystyrene mold sections typically is used to mold only one contact lens and is then disposed of.
In the above-discussed automated contact lens production system, it is desirable to eliminate or to minimize any exposure of the hydrophilic monomer to oxygen. Correspondingly, it is desirable to eliminate or minimize the exposure of the lens mold sections to oxygen. Therefore, when polystyrene mold sections are made and then used in the above-discussed manner, it is desirable to transfer these mold sections quickly from the mold in which they are made, to a low oxygen (preferably nitrogen) environment. It is difficult to achieve the desired transfer speed with conventional robot assemblies or controls because presently available robots do not move fast enough and precise enough to get in and out of the mold with the desired speed. In particular, if these robots are moved with the necessary speed, they tend to waffle and shake undesirably as they come to a sudden stop, and the movements of the robot are not sufficiently precise. If the robots are slowed down to move more precisely, the robots no longer have the desired speed.
Also, in the above-mentioned automated contact lens production system, the contact lens mold sections may not be fully solidified when they are ejected from the mold in which they are made. It is, therefore, important that any robot or apparatus which is used to carry the lens mold sections away from that mold not interfere with the desired optical qualities of the contact lens mold sections. In particular, it is important that any such robot or apparatus absorb the energy of the lens mold sections as they are transferred to that robot or apparatus without altering the shape, form or dimensions of the lens mold sections. That robot or apparatus must, likewise, be able to carry the lens mold sections in a manner that permits those lens mold sections to cool and completely harden in the desired manner.
In addition, in order to maximize the optical quality of the contact lenses, it is preferred that the optical surfaces of the polystyrene mold sectionsxe2x80x94that is, the surfaces of those mold sections that touch or lie against the hydrophilic monomer as the lens preform is being moldedxe2x80x94not be engaged or touched by any mechanical handling equipment, as the mold sections are transported and positioned in the lens molding system.
An object of this invention is to provide an improved apparatus for removing articles from molds.
Another object of this invention is to remove articles, which may not be completely hardened, from a mold and to carry those articles away from that mold without causing undue plastic deformations of the articles.
Another object of the present invention is to provide a high speed apparatus for removing fragile articles from a mold in which those articles are made, and then transporting those articles to and depositing those articles in a high speed, automated manufacturing system.
A further object of this invention is to transport articles made from the family of thermoplastics, such as polystyrene, from a mold in which those articles are made, and into a low oxygen environment of an automated contact lens molding system, in less than 12 seconds.
Another object of the present invention is to remove a plurality of discrete molded articles from a mold with the molded articles arranged in a matrix array, and to selectively either preserve that matrix array during subsequent handling of the molded articles, or reorient the matrix and the relative spacing of the articles therein according to a second predetermined matrix.
These and other objectives are attained with an apparatus for removing and transporting articles from a mold, which apparatus generally comprises first, second, and third robots or material handling assemblies. The first assembly removes the articles from the mold at the first location and transports the articles to a second location, the second assembly receives the articles from the first assembly at that second location and transports the articles to a third location, and the third assembly receives the articles from the second assembly and transports the articles to a fourth location. These locations may be selected from an infinite set of specific locations; and these first, second, third, and fourth locations may change from time to time and from application to application.
An alternate embodiment of the present invention further comprises a first intermediate assembly, disposed between the first and second assemblies, in which embodiment the articles are transported from the first assembly to the first intermediate assembly, and said intermediate assembly transports the articles to the second assembly.
Still another embodiment of the present invention further comprises a second assembly which changes the relative position of the articles disposed therein while transporting same from the second location to the third location, such as moving the articles closer together along one axis and into a denser packed array. This embodiment further comprises a third assembly which alters the order of the matrix of articles.
In each embodiment it is preferable that the first material handling assembly include a receiving means for retrieving and transporting articles from the mold to the second location. In several embodiments it is preferable that the receiving means be a hand having fingers to receive the articles from the mold and to hold the articles. In other embodiments the first assembly comprises a vacuum plate having recesses therein for receiving and securably holding the articles during translation. With respect to all of the embodiments, the receiving means is mounted to a support subassembly which, during operation, reciprocates along an axis, whereby its distal end moves into and out of a proximal position with respect to the locus of mold section fabrication. The receiving means is mounted on the support subassembly in a manner which permits sliding motion along the same axis of reciprocation so that it may reciprocate along the support subassembly from one end to the distal end. It is understood that the sliding action of the receiving means, relative to the support subassembly, may be actuated by a motive driver of either the receiving means or the support subassembly. The receiving means may, thereby, reciprocate between the locus of mold section fabrication and the second location in accordance with the proper selection of reciprocation rates of the receiving means and the support subassembly.
In addition, the first material handling assembly further comprises a means for rotationally pivoting the receiving means between a substantially vertical orientation and a substantially horizontal orientation. It is understood that either the receiving means or the support subassembly may comprise a rotating actuator which drives the rotation.
In the embodiments in which the receiving means is a hand, the fingers and the hand are preferably compliant, or are otherwise capable of dampening the energy of the articles, so that transportation of the articles from the locus of fabrication to the second location does not cause any undesirable plastic deformation of the articles, even if those articles are not completely solidified when they are received by the hand. In embodiments in which the receiving means is a vacuum plate having recesses, the mounting of the plate to the subassembly is preferably resiliently biased so that it is similarly dissipative of mechanical energy imparted during article transference.
The second material handling assembly preferably includes a generally horizontal platform having receiving ports in its surface which receive the articles when deposited by the first assembly. The second assembly translates horizontally from the second location to the third. In certain embodiments it is additional desired that the platform be mounted on a support frame having means for move the platform vertically as well as horizontally at the second location and/or the third. During operation, the first assembly transports the articles from the locus of fabrication to the second location and deposits the articles into the receiving ports in the surface of the platform. In those embodiments in which the second assembly moves vertically as well, the assembly moves up to receive the articles, descends after the articles have been received, and translates horizontally to the third location.
At the third location a third assembly retrieves the articles from the second assembly and transports them to the fourth location, which may be, for example, a pallet. In the preferred variation of several embodiments, the third assembly comprises a rotating platform which rotates the articles being transported by 90 degrees within the horizontal plane. This reorientation is necessary for use in manufacturing environments having pallets, or other receiving means, at the fourth location which are oriented orthogonally with respect to the orientation of the matrix of articles being fabricated and transported by the first and second assemblies.
In a variant of this embodiment, a first intermediate assembly is disposed between the first and second assemblies, which intermediate assembly flips the articles with respect to their vertical orientation, so that the articles are properly positioned for later assembly. In such an embodiment the first assembly transports the articles from the first location, which is the mold station, and deposits the articles into recessed ports in the first intermediate assembly. Once the articles have been positioned within the first intermediate assembly, the assembly rotates about an axis in the horizontal plane, therein flipping the articles with respect to their vertical orientation, and deposits them into the ports of the second assembly. In a preferred variation of this embodiment, the first intermediate assembly is mounted to both a means for rotating it as well as a means for translating the platform vertically so that the ports thereof may be raised in close spaced relation to the receiving means of the first assembly for accurate deposition of the articles in the ports, while also more closely approaching the second assembly during transference of the articles therefrom to the second assembly.
In the preferred variation of the alternative embodiment in which the second and third assemblies reorient the articles transported thereby, the second assembly comprises moving blocks on which the articles are deposited by the first assembly, and which draw together or spread by means of reciprocating elements, thereby altering the relative spacing of the articles. In addition, the transference of the articles from the second assembly to the third assembly is carried out in multiple steps whereby the order of the distribution matrix may be altered.
The reoriented and redistributed matrix of articles is then transported to the fourth location by the third assembly. In this preferred variation the design of the third material handling assembly includes a plurality of receiving plates having fingers for grabbing and releasably holding the articles and a support track to which it is mounted. During operation, the receiving plate descends to the third position where it removes the articles from the second assembly platform ports via the grabbing function of the fingers. The receiving plates and the articles are then raised and transported to the fourth location, during which translation the receiving plates may be drawn together to further tighten the distribution of the articles. Once the third assembly has reached the fourth location, the articles are lowered and deposited, for example into pallets in which the articles may be carried to the lens fabrication stations.
Further benefits and advantages of the invention will become apparent from a consideration of the following detailed description given with reference to the accompanying drawings, which specify and show preferred embodiments of the invention.